Company says it is not looking to compete with makers of other programs

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Microsoft Tuesday released its first free anti-virus software called Microsoft Security Essentials for computers running its Windows operating system.

The company said it is not looking to compete with commercial makers of software, such as Symantec and McAfee, but rather to "encourage broader adoption of anti-virus protection across the consumer audience," said Amy Barzdukas, general manager for consumer security at Microsoft, in a statement. (Msnbc.com is a joint venture of Microsoft and NBC Universal.)

The software has been available for testing since June, and its release comes about three weeks before the company's newest version of Windows, Windows 7, goes on sale Oct. 22. Security Essentials works with Windows XP (Service Packs 2 or 3), Windows Vista and Windows 7.

Microsoft Security Essentials uses "real-time protection to help prevent PCs from becoming infected, and it is the first Microsoft security product to make use of the company’s new Dynamic Signature Service, a technology that helps ensure users stay protected by the most current virus definitions available without having to wait for the next scheduled download," the company said.

Michael Cherry, research vice president, operating systems for Directions on Microsoft, an independent research group, has been among those trying out Security Essentials, which he said "provides a base level of protection from malware."

Malware, or malicious software, can be used to steal passwords or commandeer computers for criminal uses, including as denial-of-service attacks to shut down Web sites.

"I see this product as being used by people who do not bother to renew the trial version of anti-malware software that comes with their computer, and therefore, are unprotected once the signature file stops updating," he said. "There is still room for higher-end services," including those that "include overall PC health tools into one integrated package."

A spokesman for Symantec, maker of Norton AntiVirus and other security software, said, "While we applaud any vendor that heightens consumer awareness of the need for computer security, it’s clear that the threat landscape has moved on from the product Microsoft is launching.

"Microsoft Security Essentials is a stripped-down version of their old (Windows Live) OneCare product which was poorly rated by industry experts and users alike. From a security perspective, this Microsoft tool offers reduced defenses at a critical point in the battle against cyber crime.

"Unique malware and social engineering tricks fly under the radar of traditional signature-based technology alone — which is what is employed by free security tools such as Microsoft’s."

A Microsoft spokesperson said that Security Essentials "is not OneCare," which was a retail product, but is a "new product" from the company.

So far, Security Essentials has received positive reviews. Anti-virus testing company AV-Test GmbH used the beta version of Security Essentials and told Computerworld magazine that "All (viruses) were properly detected and treated by the product. That's good, as several other (anti-virus) scanners are still not able to detect and kill all of these critters yet."

In a statement, McAfee said the company does not feel threatened by Security Essentials, which is among a "number of free products already available" in the marketplace.

"On a level playing field, we are confident in our ability to compete with anyone who might enter the marketplace," McAfee said.

The best candidates for Security Essentials may be those who don't use any anti-virus protection on their computers. Having more than one anti-virus program on a PC can cause software conflicts and other problems.

Security Essentials will automatically be updated daily as it checks for viruses, spyware and other malicious software, Microsoft said, and "is designed to run quietly in the background alerting users only when there is an action for them to take. It also limits CPU and memory usage."